[Dovecot] Dovecot MTA

[Nick Edwards]

On 11/9/13, Timo Sirainen <tss at iki.fi> wrote:
> On 9.11.2013, at 5.11, Nick Edwards <nick.z.edwards at gmail.com> wrote:
>
>> On 11/9/13, Michael Kliewe <mkliewe at gmx.de> wrote:
>>> Hi Timo,
>>>
>>> I would also, like others, see you mainly working on Dovecot as an IMAP
>>> server. As far as I can see there are many things on the roadmap, and I
>>> hope many more will be added (for example a built-in health-checker for
>>> director backends).
>>>
>>> Only if you have enough personal resources and Dovecot as an IMAP server
>>> will not "loose your attention", I would love to see your expertise in
>>> making a better MTA.
>>
>> Yes, some of us have been waiting for some years now, for a
>> configurable change to alter the method of dovecots method of
>> failover, which is just load balancing between servers rather than
>> true failover, like postix, I see now why it gets no importance.
>
> Ah, you’re talking about SQL connections. Had to look up from old mails what
> you were talking about. It hasn’t changed, because I think the current
> behavior with load balancing + failover is more useful than failover-only.
> And you can already do failover-only with an external load balancer. Sure,
> Dovecot could also implement it, but it’s not something I especially want to
> spend time on implementing.
>

My employer has 18 pop3 servers, one imap customer access (imap here
has so little use we cant justify a redundant machine, not for 11,
yes, eleven only users after 2 years of offering imap , and 2 imap
(webmail).

Sp, each server has a replicated mysql database

If I use your "better" method, I have 18 machines polling themselves
and the MASTER server, this needlessly slams the daylights out of  the
master as I'm sure even you can imagine.

We have 4 customer relay smtp servers and 4 inbound smtp servers,
postifx, using its failover and "better" method, means they only hit
the master server when the local mysql unix socket is not listening,
ie, mysqld  is stopped -  the master server NEVER sees them.

How is your method, "better" than true failover like method used by
postfix, your methods is load balancing, it is not failover, and
causes problems on larger networks

I'm sure in some cases most people using it are happy and wont have
performance increases noticeable, but if you are going to offer a
backup for auth, it really shoulds be able to configure, if we want it
to DoS our master, or only talk to master when it cant talk local, so
I think it should be matter you need to consider, else you are only
half arsed doing it, and like implying we should go introduce a
further point of failure, by using yet more third party softwares